A positioning system for a mobile station (MS) is practically used in a wireless communication network, for example, in a cellular phone network. In such a system, a MS sends measured information to a positioning server (PSV) set up in the network and the MS is able to obtain its own location information computed by the PSV. More specifically, the MS measures a Global Positioning System (GPS) signal from GPS satellites and apparent signal delays from base stations (BS) synchronized to the GPS. The MS sends the measured information to the PSV. The PSV executes computing for positioning of the MS (location computing) based on the information sent by the MS, and notifies the MS of the computed location.
It is necessary for location computing that the total of the BSs whose apparent signal delays are measured and the GPS satellites which are captured should be three at a minimum. If the total is three, the two-dimensional location (latitude, longitude) of the MS can be determined. If the total is not less than four, the three-dimensional location (latitude, longitude, altitude) of the MS can be determined.
However, since the MS directly sends the PSV the information measured or gathered even if the above information necessary for the location computing is insufficient and awaits a response from the PSV, it results in the failure of positioning due to the failure of computing. Accordingly, unnecessary accesses to the PSV and unnecessary computing in the PSV are performed, causing waste of time and resources.